This invention pertains to ion balance monitor methods and apparatus. The ion balance monitor monitors the ion output and ion balance of the ionizer and indicates the status of the ionizer to an operator. Such ion balance expedients are useful in controlling the desired balance or desired degree and type of imbalance of positive and negative ions in gas environments. More particularly, the invention is useful in connection with air blowers and charged electrode ion emitters as are used in controlling the ionization polarity in rooms or other spaces. Such control is useful in many fields, as in controlling the ionization of the air in clean rooms in which microchips are manufactured, as a single example.
There is a need to monitor ionizers for (1) ion output and (2) ion balance. This is fairly easy to achieve with DC ionizers by monitoring the DC current due to ionization in the return of the power supply. It is more difficult to do with AC ionizers, especially of the self-balancing type, due to lack of return on power supply and the fact that AC ionization current is very small as compared with other currents in the AC high voltage circuit.
Some prior attempts have been made to monitor the ion balance in an ionizer. Known attempts include U.S. Pat. No. 4,477,263. This patent discloses a DC grid with a sensor system to monitor the balance. The balance is sensed in the room and is manually adjusted to a null meter reading on the controls.
U.S. Pat. No. 4,630,167 discloses a plate sensor in the work area and an infrared link to control ion balance in a pulsed DC system having spaced apart emitters.
U.S. Pat. No. 4,809,127 discloses a pulsed DC system of air ionizers. The ion current is sampled through a resistor and is used to regionally adjust the emitter output.
U.S. Pat. No. 4,901,194 discloses sequenced positive and negative pulses. The ion current with an integrating feature maintains average ion conditions in the room and controls the pulse generators.
U.S. Pat. No. 4,951,172 discloses a guarded sensor/control system. The sensor is a guarded probe placed in the work area.
There are of course many patents relating to ion balance. These include the following U.S. Pat. Nos.: 2,264,495; 2,879,395; 3,714,531; 4,423,462; 4,092,543; 3,936,698; 4,740,862; 4,757,422; 4,872,083; 5,008,594; 5,055,963; 5,153,811; 3,711,743; 4,435,195; 5,047,892; 5,057,966; 4,476,514; 4,528,612; 4,974,115; 4,542,434; 4,878,149; 4,642,728; 4,757,421; and 4,785,248.
The monitor of the present invention senses the high voltage alternating current in the emitter and senses the reference circuits of the ionizer. The sensing circuits are capacitively coupled to the emitter and reference circuits. Faults may be detected and displayed on trip alarm light emitting diode displays or by other output signals. The output signals may be used to automatically adjust the system by known means. Capacitive coupling used in this way is believed to be novel. The invention permits the monitoring function to be accomplished without interfering with the operation of the self-balancing circuit.
It is accordingly an object of the present invention to monitor ionizers for ion output and ion balance.
Another object is to monitor ionizers for ion output and balance in AC ionizers, particularly of the self-balancing type.
Still another object is to monitor high voltage and ion output and ion balance in self-balancing ionizers by sensing AC high voltage in both high voltage emitter and reference circuits.
There are certain typical, though rare, faults that adversely affect the ion balance. Faults that produce no ion output, such as a dead transformer, the emitter shorted to ground, or the emitter shorted to reference, etc., result in zero or very low AC voltage to ground in the emitter circuit. Faults that result in ion imbalance, such as the reference shorted to ground, result in a zero or very low AC voltage to ground in the reference circuit. In the present invention, the emitter and reference circuits are capacitively coupled with the sensing circuits whereby normal and abnormal operation are sensed without interfering with the function of the self-balancing circuit. This sensing is accomplished by performing a peak detection of the AC signal present on both the emitter and reference circuits, separately. These peak detected signals are then passed on to circuits with variable thresholds. The comparator circuits are used to trip alarm LEDs when the peak detector levels fall below the thresholds. Optional output signals of any desired other kind can be derived from these processed signals by known conventional means.
Still other objects and advantages of the present invention will become readily apparent to those skilled in this art from the following detailed description, wherein only the preferred embodiments of the invention are shown and described, simply by way of illustration of the best mode contemplated of carrying out the invention. As will be realized, the invention is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the invention. Accordingly, the drawing and description are to be regarded as illustrative in nature, and not as restrictive.